The quality of the feedwater that goes into a boiler system is in many ways similar to the nutrition used to fuel your body. If you take in the right nutrients and maintain a balanced diet, you generally feel pretty good. However, if you digest something that is not good, you can feel poorly; and if you continue an unhealthy pattern it can result in more serious issues down the road. The same is true for process equipment. The American Society of Mechanical Engineers (ASME) has established feedwater quality standards to help keep systems in good health. Pretreatment is the very heart of a system, and if pretreatment equipment is not well maintained and producing high-quality feedwater, your equipment downstream will see higher levels of scale and corrosion and decreased equipment life. Consistent maintenance on all pretreatment equipment is the most important thing you can do maximize efficiency.
Why Do We Pretreat Water for Industrial Processes?
Pretreatment is essential in keeping your boiler systems running at peak performance. The raw water quality coming into a facility can vary considerably depending on its source. Pretreatment improves water quality by removing suspended solids and other impurities to deliver consistent, high-quality feedwater to boilers. Because chemicals can only do so much, some form of pretreatment is needed for almost all applications to prevent scale and deposits and maximize efficiency.
Types of Pretreatment Equipment and What They Do
- Dealkalizers - Reduce alkalinity by utilizing ion exchange – exchanging carbonate ions for chloride ions. High alkalinity can cause condensate return line corrosion and excessive boiler blowdown.
- Demineralizers - Utilize ion exchange for removal of all anions and cations.
- Softeners - Remove calcium, magnesium and iron by utilizing ion exchange – exchanging unwanted ions for sodium. Remove hardness to decrease scale potential.
- Reverse Osmosis Systems - Reduce total dissolved solids (TDS) by means of filtration using a semi-permeable membrane. Reducing TDS in a system results in less blowdown and increased cycles of concentration. RO systems remove a broader spectrum of contaminants rather than exchange them for something else.
- Media Filters - Separate suspended and colloidal impurities to remove them from the water.
Preventive Maintenance and System Checks
There is the potential for increased operational costs when equipment is not maintained on a regular basis. Below is a list of some of the main things that you should check regularly:
- Visual inspection of system for leaks or other issues. Not just external leaks – but internal leaks, which are more common and are a bigger concern.
- Document water testing results to make sure things are in range. Tracking and trending of this data can provide indicators of declining system performance or a system failure.
- Check mechanical operations on equipment, including meters, pumps and valves. Rebuild valves per manufacturer's guidelines when necessary, replace worn gaskets and seals that deteriorate over time.
- Flows and pressures should be tracked regularly on the RO. When the pressure drop increases and the flows decrease, an RO cleaning is needed.
- RO systems should be cleaned on a regular basis. The frequency depends on the makeup water quality (loading), RO runtime, and water quality needed. A cleaning requires the circulation of specialty cleaners to remove the contaminants trapped on the membrane surfaces to keep it running at peak performance. Check the condition of membranes. Membranes will need to be replaced roughly every 3-5 years. Membranes can be cleaned onsite or offsite – this is a question of economics and capabilities. Smaller membranes are cheaper to replace than clean. Dirty membranes can significantly reduce flow, causing stress on the system and longer runs to produce the same amount of water. This costs you energy!
- Ever hear of a brine elution study on softeners and dealkalizers? These should be conducted once every 2 years to make sure the least amount of salt is being used to make the highest quality water. Think of your car, sure it starts and gets you around, but are you getting the 24 mpg you used to? What if a MAP or O2sensor has failed? What if one of your spark plugs is not firing and you are running on 5 cylinders instead of 6 (I feel that way some days). Are you getting the fuel efficiency you should be? How else would you know unless a trained mechanic diagnoses the problem? Brine elution studies have resulted in saving customers thousands of lbs of salt, lengthened service runs, and water savings. Many of these elution studies were done as a routine service and not because the system was experiencing a problem.
- Check the programming and parameters on equipment to make sure equipment is running as expected and at optimal efficiency. Make adjustments if needed. Improperly programmed equipment can cost you water, salt or water quality issues. I see it all the time. If a system is not performing well, some technicians will just ‘fool’ the programming to ‘correct’ the problem but in reality they are just masking the problem. For example: turning back the service volume on a softener due to hard water upsets. There was actually something wrong in the brine tank, but instead of fixing that – they masked the problem costing the facility more water and salt usage. If you are not guilty of doing this yourself, you certainly know someone who is.
- Work with your water treater to discuss questions, concerns, or anything that seems irregular. A good water treater will take a deeper dive into your equipment – just as a good mechanic will do when you take your car into a dealership.
Benefits of Pretreatment
- Maximize boiler efficiency by feeding consistent and high-quality feedwater
- Minimize corrosion and improve heat transfer
- Easier to control chemistry – reduced chemical demand
- Avoid plant downtime
- Avoid emergency service on pre-treatment equipment
- Prolong equipment life
I often ask myself “why don’t my customers pay more attention to their pretreatment systems?” Seems like a simple question. This equipment is critical to their process, the longevity of their equipment, how efficient it runs, and the results they are trying to achieve. I have seen time and time again where the pretreatment fails, causing major pains for the customer. So, “why don’t customers pay more attention to these assets?”
After being in this business for nearly 30 years, I think I have the answer. THE PRETREATMENT EQUIPMENT IS TOO RELIABLE. The technology is tested, proven, and simply does not break down very often. Much like your automobile, especially the new ones, they are extremely reliable and don’t require much attention or maintenance. However, when they fail – you're stuck on the side of the road. Do you change the oil as scheduled? Check all the fluids, belts, change the filters, or check the tread depth on a tire? If not, your car will eventually fail and either leave you stranded when its -10°F outside and will likely cost you more in repairs than it would have for the preventative maintenance.
I view your pretreatment equipment the same way. If we don’t pay attention to the little things along the way, you will be left stranded or paying more to get it running again. Sure, you test the conductivity on the RO or hardness levels on the softener. You are likely getting satisfactory results a majority of the time. But, is your system running efficiently? Are there internal leaks causing water quality issues? Are seals, pistons, valves, and other components about to fail – leading to an emergency call?
If you want the freedom of knowing your equipment will be properly maintained by experienced professionals on a regular contracted schedule, ask about our FreedomPlus Pretreatment Program. Good preventive maintenance helps ensure a healthy system. A pretreatment service program improves efficiency, reduces downtime and prolongs the life of your equipment. For more information contact Watertech at 414.425.3339 or request a site survey and one of our technical engineers will be in touch.
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Jeff Freitag – Director of Sales, Watertech of America, Inc.
Jeff has been in the water treatment industry for over 30 years and has a diverse background in water chemistry, pretreatment equipment, filtration, chemical feed and control, testing and monitoring, training, and consulting. He joined the Watertech team in 2000 and has held several positions before moving into his current role as Director of Sales. Some call him “Jeff.” Most who have worked with him simply refer to him as “The Water Guy!” |